Voltage-controlled slow light in an integrated semiconductor structure with net gain.

Area of Science:

• Semiconductor device physics
• Microwave photonics
• Quantum optics

Background:

• Coherent population oscillations (CPO) offer a pathway to control light propagation in semiconductor materials.
• Electromagnetically induced transparency (EIT) is a related phenomenon enabling optical switching and delay.

Purpose of the Study:

• To demonstrate a monolithically integrated semiconductor device utilizing CPO for voltage-controlled group velocity tuning.
• To explore the application of this device for true-time delay in microwave photonics.
• To investigate the underlying physics of CPO and its relation to EIT, particularly achieving transparency with partial absorption line saturation.

Main Methods:

• Fabrication of a monolithically integrated semiconductor device.
• Application of voltage control to tune the group velocity of light.
• Utilizing sections of slow and fast light (absorption and gain) to control signal properties.

Main Results:

• Achieved voltage-controlled tuning of group velocity, resulting in phase shifts up to 55 degrees at 10 GHz.
• Demonstrated control over both the slow-down factor and signal amplitude.
• Showcased the possibility of achieving transparency via CPO with partial absorption saturation.

Conclusions:

• The demonstrated CPO-based semiconductor device provides voltage-tunable control over light speed and amplitude.
• This technology is suitable for true-time delay applications in microwave photonics.
• The study elucidates the CPO mechanism, highlighting its potential even with partial absorption saturation.